The present invention relates to a cell for the optical measurement for measuring exactly, continuously and also effectively a sample of the minimum quantity required.
Generally, the absorbance of a liquid sample such as antibody, antigen, blood coagulation, blood serum, reaction liquid and others is measured using a device such as shown in FIG. 1. A liquid sample (2) is received by a cell of transparent glass for optical measurement.
A ray (4) having the wave length for example, of 300-500 nm is radiated from a light source (3) on one side of the cell to the sample through a slit plate (5). The absorbance of the ray (4) due to the sample (2) is detected by a detector (6) such as a photo tube on the other side of the cell.
Conventionally, in the optical measurement device such as this, so called standard cell (1) generally used has a shape of a square prism with an optical path length (L) of 10 mm as shown in FIG. (1). The sample receiving portion of the standard cell (1) is too large for optical measurement of the liquid sample (2) of anti body and others so that too much sample is required and a dense sample has to be diluted for measurement since it is hard to pass the ray of light therethrough.
Therefore, a cell of which sample receiving volume is reduced and the optical path length is shortened as shown in FIG. 2 is normally used. The cell shown in FIG. 2 has a shape of square prism like that of the standard cell (1) in FIG. (1), having an inner optical path length (L), for example, of 2-0.5 mm, this narrow portion being for receiving the sample. In this case, the defect as mentioned above is obviated.
However, simple narrowing of sample receiving portion makes the discharge of the sample once received and the cleaning of the interior of the cell difficult. Accordingly, the interior of the cell is polluted by the sample used previously; therefore, the exact value can not be obtained for the present sample. For cleaning the cell perfectly, the cell is necessary to be removed from the measuring optical path of the measuring instrument and reset to the original position for each of the measurements. It is extremely hard or impossible to effectively measure many samples one after another.